“We have a vision to grow our business in the U.S.,” said Yaz Iida, CEO of Rakuten Marketing. A big player in Japan, Rakuten has been largely absent from the U.S. despite purchasing Buy.com more than four years ago for $250 million. It would face competition from Amazon.com, eBay and, soon, Alibaba.

Slice, based in Palo Alto, Calif., had raised $32 million from investors including Rakuten and Lightspeed Venture Partners.

“There’s tremendous value in this technology to any company doing business online,” said Iida. “It all comes down to customer data.”

Slice, with about 70 employees, charges a fee to websites to use its software and access some customer data, said Chief Executive Scott Brady. The app is free for consumers.

“This was the best way for [Rakuten] to help us grow more quickly,” said Brady. He said the company been involved in 200 million transactions since its founding about four years ago.

Brady said the company would be able to sell information it learns from its users to other companies to improve their websites, particularly financial institutions who want to learn more about customers’ credit-card purchases. Slice has been developing a version of its app for use with Rakuten in Japan that Brady said he expects to roll out later this year, marking its first international expansion.

Brady said he wasn’t concerned Slice’s partners would be spooked now that the company is owned by a competitor. “The technology is what the companies are after,” he said.